Wireless monitoring device

ABSTRACT

The system of the invention includes a method for monitoring changes in the status or condition of a Container using one or more monitoring units mounted to the Container. The monitoring units preferably include a power supply, sensors using reflective energy with programmable parameters, globally-unique sensor identification, recording capability on a timeline, long term memory and the ability to rebroadcast information on RFID radio technology. Programmable monitoring hardware in the monitoring unit detects significant changes in the sensor outputs as a triggering event. The programmable monitoring hardware includes memory for storing identification information for the Container. The sensors which can include conventional devices that detect various forms of energy including visible light, infrared light, magnetic fields, radio frequency energy and sound. In one embodiment, a monitoring unit is mounted inside a shipping Container suitable for long distance transport. The triggering event can be used for tamper detection security.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority of co-pendingutility application Ser. No. 10/813,150 filed on Mar. 29, 2004 andprovisional application bearing Ser. No. 60/458,260, filed Mar. 31, 2003entitled “Tamper detection security device that monitors the presence ofthe door on a shipping container using reflective energy proximitysensors and radio frequency identification technologies.”

FIELD OF INVENTION

The invention relates to methods and systems to monitor the condition orsecurity of containers, crates or shipping cartons and recording thatinformation for transmission using Radio Frequency Identificationtechnology.

BACKGROUND OF THE INVENTION

Radio frequency identification tags (hereinafter referred to as “RFIDs”)are well-known electronic devices which have uses in many areasincluding freight transportation and retail product tracking. An RFIDworks by first recording or “burning in” identification or other datainto memory in the RFID device. Thereafter, the RFID sends the recordedidentification or other information to an RFID reading device. Aparticular advantage of RFIDs over bar code, optical characters andmagnetic storage (such as the magnetic strip on many credit cards) isthat the RFID does not require physical contact, or as is the case withoptical character and bar code readers, line of sight, between the tagand the reading device to be read. Some currently available active tagscan be read at distances up to 300 feet through typical crates andcontainers used during shipping.

RFIDs come in two varieties: active and passive. An active RFID includesa battery or other power source, and is activated by a signal from areading device. The activated RFID then broadcasts its identification orother data, which is picked up by the reading device. Some active tagshave memory chips on which data can be written and received remotely. Anadvantage of active RFIDs over passive RFIDs is that the inclusion of apower source allows the active RFID to transmit to a receiver withoutentering into an electromagnetic field to power the tag circuit. ActiveRFIDs are also generally able to transmit over a longer distance and beactivated individually. The advantage of active RFIDs has led to its usein automatic toll-paying systems, or the like.

Passive RFIDs have no power supply per se, but power is provided to theRFID circuitry by using an electromagnetic power receiver. The RFIDreading device sends power to the RFID's electromagnetic power receiver,thus powering up or turning on the RFID's circuits. Next, the passiveRFID broadcasts a response signal containing identification or otherinformation, which is then read by the reading device. Because thepassive RFID has no battery, it is less expensive and lighter. PassiveRFIDs have been in use for some time, notably in security access cardswhere the user holds the card near the card reader to unlock a door, andin clothing stores as security tags attached to clothing items.

Active tags can be contacted individually or in groups by a computerequipped with RF transmission capability (hereinafter referred to as a“Reader”). A reader can be a handheld, transportable device or it can bemounted in a fixed position.

Fixed readers work with an antenna array arranged around a portal andread all tags that pass through that portal. Fixed readers can be muchmore selective in that they read only the tags that pass through theportal. Fixed readers can also tell the direction the tag was moving asit passes through the portal and can do so at speeds at 40 or 50 milesper hour.

Proximity sensors, or sensors that can sense the presence or absence ofan object without physical contact are available in many forms. All ofthese devices have the common functionality in that they generate andtransmit or direct energy and receive back portions of that energy as itis reflected back from the target and thereby detect the presence orabsence of the target or in this case the door. Some types of thesesensors are described below. Hall Effect Sensors employ a magneticallybiased semiconductor, Hall element to sense moving objects. LightFeedback or fiber optic sensor: the emitter and receiver can be in thesame housing or side-by-side. The emitter sends out a beam of pulsed redor infrared light which is reflected directly by the target (at anyangle), it is diffused in all directions and some light is reflectedback. The receiver sees only a small portion of the original light,switching the sensor when a target is detected within the effective scanrange. Ultrasonic Proximity Sensor: This device allows for alternatetransmission and reception of sound waves. The transducer emits a numberof sonic waves which are reflected by an object, back to the transducer.After emission of the sound waves, the ultrasonic sensor will switchover to receive mode. The time elapsed between the emitting andreceiving is proportional to the distance of the object from the sensor.Radio Frequency Sensors use pulsed RF source for reference RF Powervalue, the Diode receiver is polled for average baseline value every Tseconds. Changes in baseline value reflect movement. All of the aboveitems and similar devices will hereinafter be referred to as “Sensors”.

Shipping containers, crates, cartons, and boxes (hereinafter referred toas “Containers”) have long been a target for theft and are a securitythreat because not only are items stolen out of them, but terroristdevices or contraband can be placed aside them. In the past shippingcontainers have been ordinarily protected by the use of locks or otherphysical impediments to entry. Physical seals have also been used sothat a quick visual inspection can determine if the seal has beenbroken. More recently the seals and locking devices have become moresophisticated and some contain RF devices that broadcast RF alerts whenthe seal is physically broken. Some of the RFID seals contain fiberoptic cables or wires which signal a fault when cut or broken. Somecontain micro switches, magnetic latches, or contact switches. All ofthese require some mechanical or electromechanical device to determinethe fault before it is broadcast on the RF communication tag.

SUMMARY OF THE INVENTION

The system of the invention includes a method for monitoring changes inthe status or condition of a Container using one or more monitoringunits mounted to the Container. The monitoring units preferably includea power supply, sensors using reflective energy with programmableparameters, globally-unique sensor identification, recording capabilityon a timeline, long term memory and the ability to rebroadcastinformation on RFID radio technology. Programmable monitoring hardwarein the monitoring unit detects significant changes in the sensor outputsas a triggering event. The programmable monitoring hardware includesmemory for storing identification information for the Container. Thesensors which can include conventional devices that detect various formsof energy including visible light, infrared light, magnetic fields,radio frequency energy and sound. The event can be logged for subsequentreadout and/or an immediate RF transmission can be generated. In oneembodiment, a monitoring unit is mounted inside a shipping Containersuitable for long distance transport. The sensor is disposed so thatopening and closing the Container door creates a change in the sensoroutput which is detected as a triggering event by the monitoringhardware. The triggering event can be used for tamper detectionsecurity. The status and logged information contained in the monitoringunit can be read by RF communication with any suitably equipped deviceincluding handheld devices and laptop computers.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates an embodiment of a system according to the inventionusing either handheld, laptop, or desktop computer equipped with PCIcard and antenna communicating with Monitoring Units.

FIG. 2 illustrates an embodiment of a Monitoring Unit according to theinvention.

FIG. 3 illustrates an embodiment of a Monitoring Unit according to theinvention using an RS485 serial interface to interface with differentkinds of RF devices.

FIG. 4 illustrates the use of a Monitoring Unit according to theinvention with a proximity sensor to sense and track items in a supplychain as they are placed into a Container.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various modifications to the preferred embodiments described below willbe readily apparent to those of ordinary skill in the art, and thedisclosure set forth herein may be applicable to other embodiments andapplications without departing from the spirit and scope of the presentinvention and the clam hereto appended. Thus, the present invention isnot intended to be limited to the embodiments described, but is to beaccorded the broadest scope consistent with the disclosure set forthherein.

A system 20 according to the invention is described in FIG. 1. Thissystem 20 includes one or more Monitoring Units 21 and one or moreReaders 30 which are devices for reading information from orcommunicating with the monitoring units 21 such as hand-held/mobiledevices 31, laptop computers 32, desktop computers 33 and/or dedicatedfixed position devices 34. Each Reader 30 is equipped with RF capabilitywhich for computers can be a commercially available card (not shown)that plugs into a slot in the computer. This card contains atransmitter, receiver, and an antenna. The Readers 30 preferably sendand receive radio signals to and from the Monitoring Units 21. TheMonitoring Unit 21 includes one or more sensors 22 and an RFTransmitter/Receiver 25. The RF capability can be limited totransmission only for some applications. The intelligence of theMonitoring Unit 21 is built into the Monitoring Electronics 24 whichincludes a microcomputer, memory and interface hardware for connectingto the sensors 22. The program or firmware to control the MonitoringElectronics 24 is developed using standard programming equipment andtechniques. Each Monitoring Unit 21 includes the capability of an activeRFID tag in that it has memory for storing identification informationassociated with the Container to which it is attached. The RFTransmitter/Receiver 25 can have an address or ID associated with itwhich is used to identify transmissions from it and to it that isseparate from the identification information for the Container. Anyradio device capable of being contacted directly and identified as aunique individual unit from its signal is an RFID radio and can be usedwithin the scope of this invention. Some examples are GSM cell phones,Ultrawideband radios, Satellite radios and Spread Spectrum radios. Anyof the radios described above can be substituted for RFTransmitter/Receiver 25. Since the Monitoring Unit 21 is intended to bemoved with the Container, a self-contained power supply such as abattery (not shown) is needed.

In a particular application, large numbers of the Monitoring Units 21can be used simultaneously in freight yard, warehouse, etc. VariousContainers can each be equipped with a Monitoring Unit 21. TheMonitoring Units 21 can be contacted by RF transmission and respondindividually or in groups. The distances between the Readers 30 and theMonitoring Unit 21 are a function of the actual RF Transmitter/Receiver25 and the various environmental factors such as the physicalcharacteristics of the Container, but typically distances up to 300 feetare practical and the signal can pass through a shipping Container.Active RFID technology is commercially available, and the invention canbe implemented in part using the active RFID technology. The sensors 22are used to monitor changes in the environment in the Container. Forexample, the opening and closing of a door can be detected. The sensors22 can also be used to detect movement of the cargo or intrusion intothe Container. The sensors 22 typically use reflected energy and, forexample, can sense the presence of the door by sending and receivingback reflective energy. This method utilizes no wires or fiber opticcables that need broken or cut to sound an alarm, nor does it requireswitches or electromagnetic contacts to operate or sound the alarm. Theinvention is not limited to any particular type of sensor. Sensors 22which can be usefully included in a Monitoring Unit 21 according to theinvention include conventional devices that detect various forms ofenergy including visible light, inured light, magnetic fields, radiofrequency energy and sound.

FIG. 2 illustrates an embodiment the Monitoring Unit 21 using an RFIDTag 54. This embodiment can be used as a tamper detection security. Thesensor 22 is connected to an appropriate analog interface 42 which is inturn connected to an analog-to-digital (A/D) converter 44. The analoginterface 42 may also be connected directly to the digital logic bus 46,since some microcomputer devices have A/D converters built-in. Themicroprocessor 48 executes a control program stored in memory 49. Themicroprocessor 48 and memory 49 can be part of a single integratedcircuit such as a microcomputer. The power is supplied by battery 52which is monitored by power monitor 54. In this embodiment the RFcommunication is performed by self-contained RFID Tag 54 which isconnected to the microprocessor 48. The self-contained RFID tag consistsof a RF circuit, a battery, an antenna, logic circuitry and nonvolatilememory on which a timeline is recorded as part of its software program.This timeline enables an event to be recorded and recovered along withthe time that it occurred. When a triggering event such as the openingof the door is detected by monitoring the sensor, the fault signal isstored on the volatile memory until it can be transferred to thetimeline in the self- contained RFID tag. This information can then beread by a Reader.

In accordance with a preferred embodiment of the invention, theinvention provides a method for using a Monitoring Unit 21 to monitorthe security of any container, crate or shipping carton by monitoringthe condition such as the position of the door or opening device andrecording that information for immediate or subsequent transmission.More specifically, the door's position, etc. is monitored by sendingenergy and receiving the energy back to a sensor as it is reflected offthe door. When the door is opened the energy being received by thesensor changes, and a fault condition occurs. The fault signal is thenrebroadcast immediately and/or recorded with a relative or real-timetimestamp for transmission by an RF communication signal.

This device depending on its mounting location allows the door, doorjam, doorframe, mobile opening, or removable side (hereinafter referredto as the “Door”) to be monitored using a Sensor instead of a physicalseal or an electromechanical switch. The device allows the faultcondition which is detected by the sensor when the Door is moved to berecorded with a timestamp accessible to a RFID tag where it is availablefor transmission to an RFID Reader.

The Sensor 22 is preferably placed in close proximity to the Door, cargoor other monitoring target. The maximum distance is limited by thecapability of the Sensor. The Monitoring Unit 21 can be mounted withscrews, magnets, etc. preferably on the inside of the Container. TheSensor is preferably mounted with the energy emitter and receiver aimedat the target with no impediments between the Sensor and the target.When the target moves or is disturbed the Sensor will detect thedifference or absence of the reflective energy off of the target. Thedifference or absence of energy indicating movement of the target is afault or triggering event. This Sensor 22 can be similar to thecommercially available SICK ELF Sensor in the document labeled SICTechnical Information.

A signal indicating a fault is then detected by the microprocessor 48 orother logic circuit where it is stored in the memory which may beseparate from or internal to the microprocessor or microcomputer asshown in FIG. 2. Because it is useful to know when the fault occurredand necessary to record the next fault, the microprocessor holds theinformation on the fault in its volatile memory until it can be recordedin its non-volatile memory on a relative timeline or using a time stampfrom a real-time clock. Once in non-volatile memory the information onthe fault is accessible to be read by the RFID tag 54. Once the fault isrecorded in non-volatile memory, the microprocessor clears the faultcondition from its memory and is once again available to receive thenext fault.

RFID tag 54 used in the embodiment of invention described above can be acommercially available Identec Solutions i-Q Series described in thedocument Active UHF Tag i-Q Series. The RFID tags used in this inventionare active and must have the capacity to access the fault informationincluding the timestamp or as in the case of the Identec i-Q tag have atime-stamping capability which is actually part of the tag's memorycapability. In this embodiment the Identec tag takes the faultinformation directly from the microprocessor via an outside lead andstores the fault on a timeline in the memory of the Identec tag. Theadvantage of the above method is that the timeline can be extended dueto the magnifying effect of using two devices with memory. An example ofthis is as follows: The iQtag from Identec with a 5 year battery lifeand a 32K memory can record 13,312 events or readings on a timelinewhich means to cover a shipping time of 30 days it can read the sensorevery 20 seconds. To provide adequate protection on the door the sensormust be monitored continuously or at least every couple of seconds. Oneway to accomplish this is to record the event as described above andhold it in the volatile memory for over 20 seconds until it can berecorded on the non-volatile memory which is activated every 20 secondsby the Identec tag. The disadvantage of this method is that the time ofthe fault as it is recorded is only accurate within 20 seconds. In thisembodiment the sensor is always in the on position as is the Identectag. Because the sensor records a fault when no energy is reflected backto the sensor a fault condition will always appear if the battery isdisconnected, removed, or goes bad. Likewise, proper function will beevident and indicate a successful installation when there is an absenceof a fault. This information can be read and tested using a reader atthe time of installation.

In an alternative embodiment of the Monitoring Unit 21 of the inventionthe RFID Tag 54 need not have a timeline storage capability. In thisembodiment, when the triggering event occurs the fault signal from theSensor 22 is stored on a timeline or real-time clock in the memory 49 ofthe Monitoring Unit 21 where it is available to the RF circuit to beread by a Reader. In this case the microprocessor would be programmed tomonitor the sensor continuously or turn on the sensor in predeterminedintervals to look for a fault condition. When fault occurs it would berebroadcast immediately or recorded directly on the timeline orreal-time clock in the logic circuit of the microprocessor. The samemicroprocessor would also provide memory and an interface with and logicfor the RFID circuit, in this embodiment the microprocessor can beaccessed directly via the RFID circuit to accomplish additionalfunctions such as turning the door sensor off and on. Reading the valuesfrom the sensor to determine if it is functioning correctly, changingthe gain or sensitivity on the sensor to adjust or calibrate the sensordue to differences in the sensors mounting distance from the door, orreflective values of its environment.

For the purpose of this invention it is not important whether the logiccontrolling, and monitoring the sensor and the timeline or real-timeclock are actually part of the RFID circuit and its memory or held on aseparate memory accessible to a self contained RFID tag with memory solong as the fault information is readily available for mediatetransmission or stored with a timestamp accessible for subsequenttransmission.

After the fault is recorded on the long-term memory associated with atimestamp and where it is accessible to the RFID circuit, it must betransmitted to a Reader 30 to be used. RFID tags can be read with eitherfixed or hand-held Readers. Readers can also work as re-broadcastingdevices reading the information on the tag and then transmittinginformation via a long-range technology.

An alternative embodiment of the Monitoring Unit 21 illustrated in FIG.3 uses an RS485 serial interface 62 to transmit the data from themicroprocessor 48 to the radio transmitter/receiver 25 which can be anyof the alternatives as described above. In this embodiment of theinvention the Monitoring Unit 21 is self-contained and does not relyupon the capabilities that are supplied by an RFID Tag. All functionalcontrol, logic and memory are contained within the Monitoring Unit 21and its firmware and the radio is for communication only.

The Monitoring Unit 21 contains memory that is used to store importantinformation relating to the container, such as owner name, containercontents or inventory, and contact information relating to theparticular shipment being monitored. In addition, the Monitoring Unit 21contains data that is logged from the sensor(s), such as the state ofthe container door (security alerts). Encryption of data that issensitive in nature is handled by the Readers. Thus, the applicationprograms for the Reader must encrypt the data when it is written to theMonitoring Unit 21 or RFID tag 54 memory. In this way, only authorizedReaders and users may see the data, and the select few with appropriateauthority may make changes to that data. Any unauthorized attempts toalter the data results in a breach of the electronic envelope, and oncethe electronic seal is broken, then a fault condition is raised andappropriate notifications can be made. The data can be written in athree-step encryption process: First, the data that is to be written isencrypted using RSA-standard encryption algorithms (64-bit, 128-bit or1024-bit depending on the country using the application). An initialchecksum key is stored in the data stream to be used upon decryption tocertify the data structure is intact. The resulting data is thenpreferably compressed using prior art compression methods in order toboth optimize space in tag memory as well as provide additionalscrambling of data.

Upon reading the data from the Monitoring Unit 21, the process isreversed by the Reader. At the conclusion of the decryption process, thechecksum key is tested for validity, indicating that the data has infact been returned to its original state. Depending on the authorizationof the user, portions or all of the data is made available to the user.

An embodiment of the method of the invention using the Monitoring Unit21 is as follows. A shipper loads a container with goods to be shipped.Container doors are closed, and using a handheld (or stationary) Reader,the container is recorded as “closed” by the Shipper. The Reader updatesthe Monitoring Unit 21 with a data packet including (but not limitedto): the date and time the container was registered as closed the username logged into the reader at the time the container was registered asclosed owner information, inventory information, and document locationsfor pertinent shipping information. This data is written to theMonitoring Unit 21 using the process described above. At this time, theMonitoring Unit 21 initializes, calibrates itself and begins monitoringthe sensor target: door, cargo, etc. The device will self-calibrateitself creating an average baseline value and then monitor changes inthat value which will indicate a fault. All values, or a fault (valuesthat are not within set parameters) can optionally be recordedperiodically in the memory of the RFID tag along with a real time clock.Faults will sound an alert, or the recorded record will be available forremote access using RFID technology. The monitoring process continuesuntil the container is received by a waypoint in the shipping process.Upon the Monitoring Unit 21 coming in contact with an authorized Reader,the data is then read into the application software, and the encryptionprocess is reversed, with the application software the testing integrityof data at each process step. The data is then available for review by auser. If the waypoint is the endpoint of the shipment, a user may chooseto receive the container. By doing so, the Monitoring Unit 21 isregistered as “open”.

A Monitoring Unit 21 has a command set to which it responds and whichcan vary according to the application. Each Monitoring Unit 21 has aunique address to which it responds, but preferably it will also respondto selected broadcast commands which are intended for all MonitoringUnits. The broadcast commands can include an otherwise unassignedaddress such as “00” to indicate that all units should receive thecommand. However, the units do not respond to broadcast commands, so atypical use of a broadcast command is to wake-up all units inpreparation for subsequent individual commands. A NOP command with aMonitoring Unit's address included can also be used to wake-up a unit.Another general command which should be implemented in the MonitoringUnit is “sleep.” In the sleep mode, power is conserved. Since varioustypes/embodiments of Monitoring Units are to be anticipated, anidentification number which corresponds to the type of Monitoring Unitshould be assigned and that identification number should be readable bya command (e.g. “Get Unit ID”) issued by a Reader. A command to alterthe address (e.g. “Set Address”) to which the Monitoring Unit respondsis desirable. The “Set Address” command can be helpful in avoidingaddress conflicts. Reading out the information on faults, etc., storedin the Monitoring Unit 21 is performed by a “Get Response” command. Theamount of data returned by the unit will vary with the application.

In addition to security, this invention can also be used for monitoringand tracking items as they move through a supply chain. Reference ismade to FIG. 4. A Monitoring Unit 21 equipped with an appropriate sensorcan sense the presence of objects as they move through a supply chainand broadcast that information via the various Readers described herein.Proximity sensors have long been used in the supply chain to monitor andtrigger events. Until now these sensors have been hard-wired into fixedlocations. With this invention the proximity detectors can be wireless,and therefore mobile, limited only by radio range. The firmwareprogramming in the Monitoring Unit 21 used for object tracking orcounting is different from that used for security applications. Thetriggering event does not imply a fault condition and simply needs torecorded long enough to transmitted to the Reader. As illustrated inFIG. 4 one application for this invention would be to detect objects 71,as they move from one location to another mobile location, or container72. In this application it would be important to record or note theevent on the mobile unit, especially where there were multiple mobileunits, and therefore various possibilities as to which mobile unit theobject was placed into. In this application each mobile unit would beequipped with one or more sensors 22 aimed at the opening of the mobileunit or container. Each Monitoring Unit 21 would have a radiotransmitter 25 which in this application could be transmit only. When anobject 74 is placed into the container the proximity sensor 22 in theMonitoring Unit 21 would see the event via a reflected signal andbroadcast that event via RF transmitter to a Reader which would note thespecific object being placed into specific container. By doing this itwould then be possible to track individual objects as they move into theindividual containers, and therefore track, and verify that they movedinto the correct container 72 being placed there by operators, automaticsorting equipment, etc.

In a preferred embodiment the monitoring of the sensors usesprogrammable parameters to determine when a triggering event hasoccurred. Every sensor and application environment has certain levels ofnoise or extraneous variations in its output that can be considerednormal. In order to avoid recording and transmitting irrelevantinformation, programmable parameters can be used to filter the sensoroutput. A default set of parameters is written into the MonitoringUnit's nonvolatile memory as a part of the manufacturing process. Theselected parameters for a particular sensor can be changed by a commandwhich is transmitted to and received by the Monitoring Unit 21. Examplesof parameters are sensor sample rate (how often the Monitoring Unit 21take a reading), sensitivity or threshold parameters, output type(sensor output goes active as an “On” condition or sensor output goesactive as an “Off” condition), alert signal duration (how long the alertis maintained before resetting and preparing for next notification) andboundary parameters such as max temperature, max shock, minimumradiation level, etc are set with default values at the factory.

Preferably the Monitoring Unit 21 includes a sleep mode in which poweris conserved. During sleep mode the microprocessor is put into ahibernation state to conserve power. An interrupt driven timer is set toperiodically wake-up the wake-up the microprocessor to take readings andperform other tasks. Temperature, humidity, and other static sensors areawakened at predetermined sample rates (see parameters above) andmeasurements are then taken. Since temperature, etc. can usually berecorded over time, the measurement itself is not necessarily atriggering event to record, therefore it sleeps to conserve power, themwakes up to record the current reading. The log of recorded values isreadable upon command received from a reader.

1-17. (canceled)
 18. A security system for monitoring a cargo storagecompartment, the system comprising: a cargo storage compartment; asensor capable of emitting and receiving a monitoring signal; and aradio transmitter connected to the sensor.
 19. The system of claim 18,further comprising monitoring electronics connected to the sensor, saidmonitoring electronics capable of comparing the emitted and receivedsignals of the sensor and triggering a transmission from the transmitterbased on the comparison of the emitted and received signals of thesensor.
 20. The system of claim 18, wherein said storage compartmentcomprises an access port.
 21. The system of claim 20, wherein saidaccess port is a door.
 22. The system of claim 20, wherein said sensoris mounted adjacent said access port so that signals emitted from saidsensor will impinge thereon.
 23. The system of claim 18, wherein saidcompartment has an interior and an exterior and said sensor is disposedin the interior of said compartment.
 24. The system of claim 18, whereinsaid compartment has an interior and an exterior and said transmitter isdisposed in the interior of said compartment.
 25. The system of claim18, wherein said sensor is a reflective energy sensor.
 26. A securecargo storage system, the system comprising: a cargo storage compartmentdefined by an interior and an exterior; a sensor in the interior of saidcargo storage compartment, said sensor capable of emitting energy andreceiving the emitted energy; and a radio transmitter.
 27. The system ofclaim 26, further comprising: a power supply electrically connected tothe sensor; and monitoring electronics connected to the sensor, themonitoring electronics detecting and recording changes in the emittedand received energy as a triggering event; and a radio transmitter fortransmitting information on the triggering event supplied by themonitoring electronics, the information including an identifier for themonitoring unit.
 28. The monitoring unit of claim 26 further comprisinga radio receiver for receiving commands and data from a reader.
 29. Themonitoring unit of claim 27 further comprising means for placing themonitoring electronics in a sleep mode and an interrupt driven timerwhich periodically wakes the monitoring electronics out of sleep mode.30. The monitoring unit of claim 27 further comprising means forrecording each triggering event along with a timestamp on a timeline andmeans for transmitting the timeline to the reader upon receiving acommand.
 31. The monitoring unit of claim 28 further comprising meansfor receiving data from the reader as a storage compartment identifier,the storage compartment identifier being associated with a storagecompartment in which the sensor is disposed and means for transmittingthe storage compartment identifier to the reader upon receiving acommand.
 32. The monitoring unit of claim 27 further comprising meanstransmitting a sensor identifier to the reader upon receiving a command,the sensor identifier specifying a type of the sensor.
 33. Themonitoring unit of claim 31 further comprising means for changing thestorage compartment identifier for the monitoring unit based on acommand received from a reader.
 34. The monitoring unit of claim 27further comprising means transmitting information on each triggeringevent in realtime.
 35. The monitoring unit of claim 26, wherein saidinterior is defined by a first interior surface and a second interiorsurface and wherein said sensor is attached to the first interiorsurface.
 36. The monitoring unit of claim 35, wherein said sensor ispositioned on said first interior surface so that the emitted energy canbe reflected off of said second interior surface.
 37. The monitoringunit of claim 26, wherein said interior is defined by an interiorsurface and wherein said sensor positioned in said interior so that theemitted energy can be reflected off of said interior surface.
 38. Themonitoring unit of claim 26, wherein said sensor signal is an IR signal.39. The monitoring unit of claim 26, wherein said sensor signal is anambient light signal.
 40. The monitoring unit of claim 26, wherein saidsensor is an ambient light sensor.
 41. The monitoring unit of claim 26,wherein said sensor is a proximity sensor.
 42. The monitoring unit ofclaim 37, wherein said interior surface is an access port.
 43. Themonitoring unit of claim 35, wherein said first interior surface is anaccess port.
 44. The monitoring unit of claim 42, wherein said accessport is a door.
 45. The monitoring unit of claim 43, wherein said accessport is a door.
 46. A secure cargo storage system, the systemcomprising: a cargo storage compartment having an interior surface withan access port defined in said interior surface; a sensor capable ofemitting an energy signal and receiving the emitted energy signal, saidsensor disposed in said cargo storage compartment so that the emittedenergy signal will reflect off of said access port; a power supplyelectrically connected to the sensor; monitoring electronics connectedto the sensor, the monitoring electronics detecting and recordingchanges in the emitted and received energy as a triggering event; and aradio transmitter disposed within said storage compartment fortransmitting information on the triggering event supplied by themonitoring electronics.